Iran lawmakers passed a measure — in a bill aimed at protecting the rights of children, no less — that allows for men to marry their adopted daughters, so long as the girls are at least 13 years old.

Children’s rights activists are alarmed, The Guardian in the United Kingdom reported.

“This bill is legalizing pedophilia,” said Shadi Sadr, a human rights lawyer for Justice for Iran, a legal group headquartered in London. “It’s not part of the Iranian culture to marry your adopted child. Obviously incest exists in Iran more or less as it happens in other countries across the world. But this bill is legalizing pedophilia and is endangering our children and normalizing this crime in our culture.”

A court first would have to rule that such a marriage would be in the best interest of the child, on a case-by-case basis. Girls in the Muslim nation already can marry when they’re 13 years old, with the OK of their fathers. Girls who aren’t yet 13 also can marry legally but must obtain the permission of a judge. The union of stepchildren with stepparents is currently forbidden by law.

But this new bill would change that prohibition and give stepdads the legal right to marry their stepdaughters, with the judge’s permission, The Guardian said. It still needs the final stamp of approval from the Guardian Council, the country’s body of clerics and judicial officials in charge of vetting bills before they become law.

By way of comparison, the laws regarding male marriage dictates that boys must wait until the age of 15 to legally wed.

The Iranian news site Tabnak estimates that 42,000 children between the ages of 10 and 14 were married in 2010 — and another 75 children under the age of 10 were forced to wed in Tehran in that same year.